From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 86CF04D7D21; Mon, 19 Oct 2026 10:36:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792406171; cv=none; b=mkRceGGsSsE0kfbJv1SplB+p8qF7kZleTbR7R5/GzHQ2+RZxn6AoTPtJuQNqxXirNtUEP25uJhAMt/OHQNEPompyYyzMZabUiwf472kAWWdpXGaOOpUuxGGM4DNykxegfpgssnZlHQQc0axIyPjxE0XnAQCL9pS+7dcHQZELu5g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792406171; c=relaxed/simple; bh=ZiVNxqQR/u4Ci29N2YHi05R+bfI/MdekS0OCzuSYnRI=; h=Message-ID:From:Subject:To:Cc:In-Reply-To:References:Content-Type: Date; b=eGvYuLCZVcaemtiFXEXopici/LUN8SoS5VvaHZLzRt3SCVD3CVvW6HMVMGndXMOTU59XbJUo1DQwvNzalwFNlIh8L+AN6Y/+7agxl/pVxGWrl/m6dEHUuerc2OOmawe+m68EYe5TfVYJCmJNDbn6kL6DEmusOB1tL7Hx87cbNOY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=NGb2tfKG; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="NGb2tfKG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F1F6E1F000C4; Mon, 19 Oct 2026 10:36:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792406170; bh=PI9AeKxwP0CwhGbVllNbx6krpwtM2PRvUhXT8Vzgt5M=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=NGb2tfKGnDil3eYBe7ZpO4AmaGnOXX2vMjzwldNag7D3T1wlMkCSK0DcZxZh8Jdhr eVdf4ajMa9vNotnWujq1qzu4sh2zKR1AvtODC0Wu3TSLnPbGen1OIiyGlxBm7KxNHR vkmymdGjq+Mx0ZxBsSiDSX2cS7VUElLVg2yY9YJp2xn3GA66s/RukJ5KsdqDwAgK6Y vZl+0d1jUDyyr1f5arLLUZ+zwGhyYuEBV2TAPCP9P/NKZceWY5mpEeB0iBykBBcxrl D1iwOseVSHRH6QZX4xYxA1ivwthJsx0FgeBBxFFYxdiKiy1CRW+J+r/osTUqFwG66O Xu/ruwb0r72ag== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH v2 3/3] ARM: dts: imx6q-apalis: Add VGA overlay Reply-To: sashiko-reviews@lists.linux.dev To: "Leonardo Costa" Cc: dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org, imx@lists.linux.dev, robh@kernel.org, conor+dt@kernel.org, Frank.Li@kernel.org In-Reply-To: <20261019-v2-apalis-imx6-enable-vga-v2-3-ef6a3a780472@toradex.com> References: <20261019-v2-apalis-imx6-enable-vga-v2-0-ef6a3a780472@toradex.com> <20261019-v2-apalis-imx6-enable-vga-v2-3-ef6a3a780472@toradex.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Mon, 19 Oct 2026 10:36:09 +0000 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Thank you for your contribution! Sashiko AI review found 1 potential issue(= s) to consider: - [High] ARM: dts: imx6q-apalis: VGA data-enable-active ignored by simple-b= ridge -- commit a66c8dd73182954ba43ed81cada90ae73edf93a0 Author: Leonardo Costa ARM: dts: imx6q-apalis: Add VGA overlay This commit adds a device tree overlay for the VGA output on the Apalis Evaluation Board, connecting the parallel RGB display interface to a non-programmable video DAC and VGA connector with an active-low data-enable signal, and wires up composite DTB targets in the Makefile. > diff --git a/arch/arm/boot/dts/nxp/imx/imx6q-apalis-eval-vga.dtso b/arch/= arm/boot/dts/nxp/imx/imx6q-apalis-eval-vga.dtso > new file mode 100644 > index 0000000000000..991c2b7c27773 > --- /dev/null > +++ b/arch/arm/boot/dts/nxp/imx/imx6q-apalis-eval-vga.dtso > @@ -0,0 +1,80 @@ [ ... ] > + vga-encoder { > + compatible =3D "dumb-vga-dac"; > + > + ports { > + #address-cells =3D <1>; > + #size-cells =3D <0>; > + > + port@0 { > + reg =3D <0>; > + > + vga_enc_in: endpoint { > + data-enable-active =3D <0>; > + remote-endpoint =3D <&vga_display_out>; > + }; > + }; [Severity: High] Does data-enable-active =3D <0> on vga_enc_in actually reach the IPUv3 CRTC? In simple_bridge_probe() in drivers/gpu/drm/bridge/simple-bridge.c, the data-enable-active property is parsed into timings->input_bus_flags: if (de_present && !sbridge->bridge.timings) { struct drm_bridge_timings *timings; timings =3D devm_kzalloc(&pdev->dev, sizeof(*timings), GFP_KERNEL); if (!timings) return -ENOMEM; timings->input_bus_flags =3D de ? DRM_BUS_FLAG_DE_HIGH : DRM_BUS_FLAG_DE_LOW; sbridge->bridge.timings =3D timings; } However, simple_bridge_bridge_funcs registers atomic bridge state callbacks without an .atomic_check callback: static const struct drm_bridge_funcs simple_bridge_bridge_funcs =3D { .atomic_create_state =3D drm_atomic_helper_bridge_create_state, .atomic_destroy_state =3D drm_atomic_helper_bridge_destroy_state, .atomic_duplicate_state =3D drm_atomic_helper_bridge_duplicate_state, .attach =3D simple_bridge_attach, .atomic_enable =3D simple_bridge_enable, .atomic_disable =3D simple_bridge_disable, }; During drm_atomic_bridge_chain_check() -> drm_atomic_bridge_propagate_bus_flags(), sbridge's bridge_state->input_bus_cfg.flags is overwritten with the downstream display-connector bridge's input_bus_cfg.flags (which is 0), and sbridge->bridge.timings->input_bus_flags is never copied into bridge_state->input_bus_cfg.flags. Then, upstream in imx_pd_bridge_atomic_check() in drivers/gpu/drm/imx/ipuv3/parallel-display.c: if (next_bridge) next_bridge_state =3D drm_atomic_get_new_bridge_state(crtc_state->state, next_bridge); if (next_bridge_state) bus_flags =3D next_bridge_state->input_bus_cfg.flags; else bus_flags =3D di->bus_flags; Because next_bridge_state is non-NULL, bus_flags is read as 0 from next_bridge_state->input_bus_cfg.flags without consulting next_bridge->timings->input_bus_flags. When ipu_crtc_mode_set_nofb() -> ipu_di_init_sync_panel() runs, sig_cfg.enable_pol =3D !(imx_crtc_state->bus_flags & DRM_BUS_FLAG_DE_LOW) evaluates to 1, driving the data-enable pin active-high instead of active-low and gating off the VGA DAC output during active video. Should simple-bridge implement .atomic_check to populate bridge_state->input_bus_cfg.flags from bridge->timings->input_bus_flags so the active-low polarity is propagated to imx-parallel-display? [ ... ] --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261019-v2-apalis-= imx6-enable-vga-v2-0-ef6a3a780472@toradex.com?part=3D3